Display device

ABSTRACT

A display device includes an emission area and a sub-region spaced apart from the emission area in a first direction, electrodes extending in the first direction, disposed across the emission area and the sub-region, and spaced apart from each other in a second direction, a first bank surrounding the emission area and the sub-region, and light emitting elements disposed on the electrodes spaced apart in the second direction in the emission area. The first bank includes trench portions in which a top surface of the first bank is partially depressed. The trench portions are disposed between the emission area and the sub-region.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and benefits of Korean PatentApplication No. 10-2020-0115879 under 35 U.S.C. § 119, filed on Sep. 10,2020 in the Korean Intellectual Property Office, the entire contents ofwhich are incorporated herein by reference.

BACKGROUND 1. Technical Field

This disclosure relates to a display device.

2. Description of the Related Art

The importance of display devices has increased with the development ofmultimedia technology. There have been developments in the types ofdisplay devices such as an organic light emitting display (OLED), aliquid crystal display (LCD) and the like.

A display device displays an image, and includes a display panel, suchas an organic light emitting display panel or a liquid crystal displaypanel. The light emitting display panel may include light emittingelements such as light emitting diodes (LED), and examples of lightemitting diodes include organic light emitting diodes which use organicmaterials as the light emitting material and an inorganic light emittingdiodes using inorganic materials as the light emitting material.

It is to be understood that this background of the technology sectionis, in part, intended to provide useful background for understanding thetechnology. However, this background of the technology section may alsoinclude ideas, concepts, or recognitions that were not part of what wasknown or appreciated by those skilled in the pertinent art prior to acorresponding effective filing date of the subject matter disclosedherein.

SUMMARY

Aspects of the disclosure provide a display device capable of preventingdefects such as material breakage and a short circuit in someelectrodes.

However, aspects of the disclosure are not restricted to the one setforth herein. The above and other aspects of the disclosure will becomemore apparent to one of ordinary skill in the art to which thedisclosure pertains by referencing the detailed descriptions of theembodiments given below.

The display device according to an embodiment may prevent the materialof a contact electrode, which is connected to a light emitting elementand an electrode, from being broken due to a stepped portion in thelayer below the contact electrode. Furthermore, the display device mayprevent contact electrodes from being short-circuited by residues frommaterial used to form the contact electrodes.

It should be noted that the effects of the disclosure are not limited tothose described above, and other effects of the disclosure will beapparent from the following description.

According to an embodiment, a display device may include an emissionarea and a sub-region spaced apart from the emission area in a firstdirection, electrodes extending in the first direction, disposed acrossthe emission area and the sub-region, and spaced apart from each otherin a second direction, a first bank surrounding the emission area andthe sub-region, and light emitting elements disposed on the electrodesspaced apart in the second direction in the emission area. The firstbank may include trench portions in which a top surface of the firstbank is partially depressed. The trench portions may be located betweenthe emission area and the sub-region.

The display device may further include contact electrodes disposed onthe electrodes and extending in the first direction. The contactelectrodes may be disposed across the emission area and the sub-regionthrough the trench portions of the first bank.

The first bank may include a first bank portion, a second bank portionthat may include the trench portions and may have a height lower than aheight of the first bank portion, and a bridge bank portion that may bedisposed between the trench portions and may have a same height as theheight of the first bank portion.

The display device may further include a first insulating layer coveringthe electrodes. The first insulating layer may include contact portionsthat may partially expose top surfaces of the electrodes in thesub-region.

The contact electrodes may electrically contact the light emittingelements disposed in the emission area and the electrodes exposedthrough the contact portions in the sub-region.

The display device may further comprise a second insulating layerdisposed on the first insulating layer, the first bank, and the lightemitting elements. The second insulating layer may expose ends of thelight emitting elements. The second insulating layer may be not disposedin the trench portions of the first bank.

The contact electrodes may be disposed on the second insulating layer,and may be directly disposed on the second bank portion in the trenchportions.

Each of the trench portions of the first bank may have a sidewallaligned with a sidewall of the second insulating layer disposed on thefirst bank.

The second insulating layer may include openings adjacent to the trenchportions in the emission area and exposing a top surface of the firstinsulating layer. The contact electrodes may be directly disposed on thefirst insulating layer in the openings.

The display device may further include a third insulating layer disposedon at least one of the contact electrodes and the second insulatinglayer. At least a portion of the contact electrodes may be directlydisposed on the third insulating layer in the second bank portion.

At least a portion of the contact electrodes may be disposed between thefirst bank and the third insulating layer in the trench portions.

The electrodes may include a first electrode and a second electrodespaced apart from the first electrode in the second direction. Thedisplay device may further include a first contact electrode disposed onthe first electrode and extending in the first direction, and a secondcontact electrode disposed on the second electrode and extending in thefirst direction. The trench portions may include a first trench portionin which the first contact electrode may be disposed, and a secondtrench portion in which the second contact electrode may be disposed.The second trench portion may be spaced apart from the first trenchportion in the second direction.

The electrodes may further include a third electrode spaced apart fromthe second electrode in the second direction. The first electrode may bedisposed between the second electrode and the third electrode. The lightemitting elements may include a first light emitting element that mayhave a first end disposed on the first electrode and a second enddisposed on the third electrode, and a second light emitting elementthat may have a first end disposed on the first electrode and a secondend disposed on the second electrode.

The display device may further include a third contact electrodeincluding a first extension portion that may be disposed on the thirdelectrode and may electrically contact the second end of the first lightemitting element, a second extension portion that may be disposed on thefirst electrode and may electrically contact the first end of the secondlight emitting element, and a connection portion that may connect thefirst extension portion to the second extension portion. The firstextension portion may extend in the first direction and may be disposedacross the emission area and the sub-region through the first trenchportion.

The trench portions may further include a third trench portion locatedopposite the first trench portion in the first direction with respect tothe emission area, and the connection portion may be disposed on thethird trench portion.

According to an embodiment, a display device may include an emissionarea and a sub-region spaced apart from the emission area in a firstdirection, holes disposed between the emission area and the sub-region,electrodes extending in the first direction, disposed across theemission area and the sub-region, and spaced apart from each other in asecond direction, a first bank surrounding the emission area and thesub-region and including a bridge bank portion disposed between theholes, light emitting elements disposed on the electrodes and spacedapart in the second direction in the emission area, and contactelectrodes disposed on the electrodes and extending in the firstdirection. The plurality of holes may connect the emission area to thesub-region, and the contact electrodes may be disposed across theemission area and the sub-region through the holes.

The display device may further include a first insulating layer coveringthe electrodes, and a second insulating layer disposed on the firstinsulating layer, the first bank, and the light emitting elements toexpose ends of the light emitting elements. The second insulating layermay be not disposed in the holes.

The contact electrodes may be disposed on the second insulating layerthat electrically contacts the light emitting elements, and may bedirectly disposed on the first insulating layer in the holes.

The first insulating layer may include contact portions formed in thesub-region to partially expose top surfaces of the electrodes, and thecontact electrodes may electrically contact the electrodes in thecontact portions of the sub-region.

A sidewall of the first bank around the holes may be aligned with asidewall of the second insulating layer disposed on the first bank.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the disclosure will becomemore apparent by describing in detail embodiments thereof with referenceto the attached drawings, in which:

FIG. 1 is a schematic plan view of a display device according to anembodiment;

FIG. 2 is a schematic plan view illustrating a pixel of a display deviceaccording to an embodiment;

FIG. 3 is a schematic plan view illustrating a first sub-pixel of FIG.2;

FIG. 4 is a schematic cross-sectional view taken along lines Q1-Q1′,Q2-Q2′, and Q3-Q3′ of FIG. 3;

FIG. 5 is a schematic cross-sectional view taken along line Q4-Q4′ ofFIG. 3;

FIG. 6 is a schematic plan view illustrating a schematic arrangement ofa first bank and contact electrodes disposed in a sub-pixel of a displaydevice according to an embodiment;

FIG. 7 is a schematic cross-sectional view taken along line Q5-Q5′ ofFIG. 6;

FIG. 8 is a schematic cross-sectional view taken along line Q6-Q6′ ofFIG. 6;

FIG. 9 is a schematic diagram of a light emitting element according toan embodiment;

FIGS. 10 to 15 are schematic views illustrating a portion of afabricating process of a display device according to an embodiment;

FIG. 16 is a schematic plan view illustrating a sub-pixel of a displaydevice according to an embodiment;

FIG. 17 is a schematic cross-sectional view taken along line Q7-Q7′ ofFIG. 16;

FIG. 18 is a schematic cross-sectional view illustrating a step in afabricating process of the display device of FIG. 16;

FIG. 19 is a schematic plan view illustrating a sub-pixel of a displaydevice according to an embodiment;

FIG. 20 is a schematic cross-sectional view taken along line Q8-Q8′ ofFIG. 19; and

FIG. 21 is a schematic cross-sectional view taken along line Q9-Q9′ ofFIG. 19.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosure will now be described more fully hereinafter withreference to the accompanying drawings, in which embodiments are shown.This disclosure may, however, be embodied in different forms and shouldnot be construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the invention to thoseskilled in the art.

It will also be understood that when a layer is referred to as being“on” another layer or substrate, it can be directly on the other layeror substrate, or intervening layers may also be present. The samereference numbers indicate the same components throughout thespecification.

It will be understood that, although the terms “first,” “second,” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another element. For instance, a first elementdiscussed below could be termed a second element without departing fromthe teachings of the disclosure. Similarly, the second element couldalso be termed the first element.

In the drawings, sizes, thicknesses, ratios, and dimensions of theelements may be exaggerated for ease of description and for clarity.Like numbers refer to like elements throughout.

In the specification and the claims, the phrase “at least one of” isintended to include the meaning of “at least one selected from the groupof” for the purpose of its meaning and interpretation. For example, “atleast one of A and B” may be understood to mean “A, B, or A and B.”

The spatially relative terms “below”, “beneath”, “lower”, “above”,“upper”, or the like, may be used herein for ease of description todescribe the relations between one element or component and anotherelement or component as illustrated in the drawings. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation, in addition tothe orientation depicted in the drawings. For example, in the case wherea device illustrated in the drawing is turned over, the devicepositioned “below” or “beneath” another device may be placed “above”another device. Accordingly, the illustrative term “below” may includeboth the lower and upper positions. The device may also be oriented inother directions and thus the spatially relative terms may beinterpreted differently depending on the orientations.

The phrase “in a plan view” means viewing the object from the top, andthe phrase “in a schematic cross-sectional view” means viewing across-section of which the object is vertically cut from the side.

The terms “overlap” or “overlapped” mean that a first object may beabove or below or to a side of a second object, and vice versa.Additionally, the term “overlap” may include layer, stack, face orfacing, extending over, covering, or partly covering or any othersuitable term as would be appreciated and understood by those ofordinary skill in the art.

The terms “comprises,” “comprising,” “includes,” and/or “including,”,“has,” “have,” and/or “having,” and variations thereof when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, components, and/or groups thereof, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

It will be understood that when an element (or a region, a layer, aportion, or the like) is referred to as “being on”, “connected to” or“coupled to” another element in the specification, it can be directlydisposed on, connected, or coupled to another element mentioned above,or intervening elements may be disposed therebetween.

It will be understood that the terms “connected to” or “coupled to” mayinclude a physical or electrical connection or coupling.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which the disclosure pertains. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, embodiments will be described with reference to theaccompanying drawings.

FIG. 1 is a schematic plan view of a display device according to anembodiment.

Referring to FIG. 1, a display device 10 may display a moving image or astill image. The display device 10 may refer to any electronic deviceproviding a display screen. Examples of the display device 10 mayinclude a television, a laptop computer, a monitor, a billboard, anInternet-of-Things device, a mobile phone, a smartphone, a tabletpersonal computer (PC), an electronic watch, a smart watch, a watchphone, a head-mounted display, a mobile communication terminal, anelectronic notebook, an electronic book, a portable multimedia player(PMP), a navigation device, a game machine, a digital camera, acamcorder, and the like, which provide a display screen.

The display device 10 may include a display panel which provides adisplay screen. Examples of the display panel may include an inorganiclight emitting diode display panel, an organic light emitting displaypanel, a quantum dot light emitting display panel, a plasma displaypanel, and a field emission display panel. In the following description,an inorganic light emitting diode display panel is illustrated as adisplay panel, but the embodiments are not limited thereto, and otherdisplay panels may be applied within the scope of the embodiments.

The shape of the display device 10 may be variously modified. Forexample, the display device 10 may have a shape such as a rectangularshape elongated in a horizontal direction, a rectangular shape elongatedin a vertical direction, a square shape, a quadrilateral shape withrounded corners (vertices), another polygonal shape and a circularshape. The shape of a display area DPA of the display device 10 may alsobe similar to the overall shape of the display device 10. FIG. 1illustrates a display device 10 having a rectangular shape elongated ina second direction DR2.

The display device 10 may include the display area DPA and a non-displayarea NDA. The display area DPA is an area where a screen can bedisplayed, and the non-display area NDA is an area where a screen is notdisplayed. The display area DPA may also be referred to as an activeregion, and the non-display area NDA may also be referred to as anon-active region. The display area DPA may substantially occupy thecenter of the display device 10.

The display area DPA may include pixels PX. The pixels PX may bearranged in a matrix. The shape of each pixel PX may be a rectangular orsquare shape in a plan view. However, the embodiments are not limitedthereto, and it may be a rhombic shape in which each side is inclinedwith respect to a direction. The pixels PX may be alternately disposedin a stripe type or a PENTILE™ type. Each of the pixels PX may includeone or more light emitting elements that emit light of a specificwavelength band to display a specific color.

The non-display area NDA may be disposed around the display area DPA.The non-display area NDA may completely or partially surround thedisplay area DPA. The display area DPA may have a rectangular shape, andthe non-display area NDA may be disposed adjacent to four sides of thedisplay area DPA. The non-display area NDA may form a bezel of thedisplay device 10. Wirings or circuit drivers included in the displaydevice 10 may be disposed in the non-display area NDA, or externaldevices may be mounted thereon.

FIG. 2 is a schematic plan view illustrating a pixel of a display deviceaccording to an embodiment.

Referring to FIG. 2, each of the pixels PX of the display device 10 mayinclude sub-pixels PXn (n ranging from 1 to 3). For example, a pixel PXmay include a first sub-pixel PX1, a second sub-pixel PX2 and a thirdsub-pixel PX3. The first sub-pixel PX1 may emit light of a first color,the second sub-pixel PX2 may emit light of a second color, and the thirdsub-pixel PX3 may emit light of a third color. For example, the firstcolor may be blue, the second color may be green, and the third colormay be red. However, the embodiments are not limited thereto, and thesub-pixels PXn may emit light of the same color. Although FIG. 2illustrates that a pixel PX includes three sub-pixels PXn, theembodiments are not limited thereto, and the pixel PX may include alarger number of sub-pixels PXn.

Each sub-pixel PXn of the display device 10 may include an emission areaEMA and a non-emission area (not shown). The emission area EMA may be anarea where the light emitting elements ED are aligned to emit light of acertain wavelength band. The non-emission area may be an area wherethere are no light emitting elements ED and the light emitted from thelight emitting elements ED do not reach, so that no light is emitted.The emission area may include an area in which the light emittingelement ED is disposed, and an area adjacent to the light emittingelement ED to emit light emitted from the light emitting element ED.

Without being limited thereto, the emission area may also include anarea in which the light emitted from the light emitting elements ED isreflected or refracted by another member and emitted. The light emittingelements ED may be disposed in each sub-pixel PXn, and the emission areamay be formed to include an area where the light emitting elements EDare disposed and an area adjacent thereto.

Although it is shown in the drawing that the sub-pixels PXn have theemission areas EMA that are substantially identical in size, theembodiments are not limited thereto. In some embodiments, the emissionareas EMA of the sub-pixels PXn may have different sizes according to acolor or wavelength band of light emitted from the light emittingelement ED disposed in each sub-pixel.

Each sub-pixel PXn may further include a sub-region SA disposed in thenon-emission area. The sub-region SA may be disposed at a side of theemission area EMA in the first direction DR1, and may be disposedbetween the emission areas EMA of the sub-pixels PXn adjacent in thefirst direction DR1. For example, the emission areas EMA and thesub-regions SA may be repeatedly arranged in the second direction DR2,respectively, while being alternately arranged in the first directionDR1. A first bank BNL1 may be disposed between the sub-region SA and theemission area EMA, and the gap therebetween may vary according to thewidth of the first bank BNL1. Light may not be emitted from thesub-region SA because the light emitting element ED is not disposed inthe sub-region SA, but an electrode RME disposed in each sub-pixel PXnmay be partially disposed in the sub-region SA. The electrodes RMEdisposed in some of the sub-pixels PXn may be separated in thesub-region SA.

The first bank BNL1 may include a portion extending in the firstdirection DR1 and the second direction DR2 in a plan view to be arrangedin a grid pattern over the entire surface of the display area DPA. Thefirst bank BNL1 may be disposed along the boundaries between thesub-pixels PXn to delimit the neighboring sub-pixels PXn. Furthermore,the first bank BNL1 may be disposed to surround the emission area EMAand the sub-region SA disposed for each sub-pixel PXn to delimit themfrom each other.

According to an embodiment, in the display device 10, the first bankBNL1 may delimit the adjacent sub-pixels PXn from each other andsurround the emission area EMA and the sub-region SA. The first bankBNL1 may include trench portions TP disposed between the emission areaEMA and the sub-region SA. The first bank BNL1 may include the trenchportion TP having a height lower than the portion of the first bank BNL1at the boundary between the sub-pixels PXn, so that a height differencecaused by the first bank BNL1 can be decreased between the emission areaEMA and the sub-region SA.

FIG. 3 is a schematic plan view illustrating a first sub-pixel of FIG.2. FIG. 4 is a schematic cross-sectional view taken along lines Q1-Q1′,Q2-Q2′, and Q3-Q3′ of FIG. 3. FIG. 5 is a schematic cross-sectional viewtaken along line Q4-Q4′ of FIG. 3. FIG. 3 illustrates a first sub-pixelPX1 included in a pixel PX, and FIG. 4 illustrates a cross-sectionthrough both ends of the light emitting elements ED disposed in thefirst sub-pixel PX1. FIG. 5 illustrates a cross-section of contactportions CT1, CT2, and CT3 to which the electrodes RME and contactelectrodes CNE are connected.

Referring to FIGS. 3 to 5 in conjunction with FIG. 2, the display device10 may include a first substrate SUB and a semiconductor layer,conductive layers, and insulating layers disposed on the first substrateSUB. The semiconductor layer, the conductive layers, and the insulatinglayers may each constitute a circuit layer CCL and a display elementlayer of the display device 10.

The first substrate SUB may be an insulating substrate. The firstsubstrate SUB may be made of an insulating material such as glass,quartz, or polymer resin. The first substrate SUB may be a rigidsubstrate, but may also be a flexible substrate which can be bent,folded, or rolled.

A first conductive layer may be disposed on the first substrate SUB. Thefirst conductive layer includes a lower metal layer BML that is disposedto overlap an active layer ACT1 of a first transistor T1. The lowermetal layer BML may include a material of blocking light to preventlight from reaching the active layer ACT1 of the first transistor T1.However, the lower metal layer BML may be omitted.

The buffer layer BL may be entirely disposed on the lower metal layerBML and the first substrate SUB. The buffer layer BL may be formed onthe first substrate SUB to protect the transistors of the pixel PX frommoisture permeating through the first substrate SUB susceptible tomoisture permeation, and may perform a surface planarization function.

The semiconductor layer is disposed on the buffer layer BL. Thesemiconductor layer may include the active layer ACT1 of the firsttransistor T1. This may be disposed to partially overlap a gateelectrode G1 of a second conductive layer, which will be describedbelow.

The semiconductor layer may include polycrystalline silicon,monocrystalline silicon, oxide semiconductor, and the like. In anembodiment, the semiconductor layer may include polycrystalline silicon.The oxide semiconductor may be an oxide semiconductor containing indium(In). For example, the oxide semiconductor may be at least one of indiumtin oxide (ITO), indium zinc oxide (IZO), indium gallium oxide (IGO),indium zinc tin oxide (IZTO), indium gallium tin oxide (IGTO), indiumgallium zinc oxide (IGZO), and indium gallium zinc tin oxide (IGZTO).

In the drawing, only the first transistor T1 is illustrated among thetransistors included in the sub-pixel PXn of the display device 10, butthe embodiments are not limited thereto, and the display device 10 mayinclude a larger number of transistors.

The first gate insulating layer GI may be disposed on the semiconductorlayer and the buffer layer BL. The first gate insulating layer GI mayfunction as a gate insulating layer of each transistor.

The second conductive layer may be disposed on the first gate insulatinglayer GI. The second conductive layer may include the gate electrode G1of the first transistor T1. The gate electrode G1 may be arranged tooverlap the channel region of the active layer ACT1 in the thirddirection DR3 which is the thickness direction. Although not shown inthe drawing, the second conductive layer may further include acapacitance electrode of a storage capacitor.

A first interlayer insulating layer IL1 may be disposed on the secondconductive layer. The first interlayer insulating layer IL1 may functionas an insulating layer between the second conductive layer and otherlayers disposed thereon, and may protect the second conductive layer.

A third conductive layer may be disposed on the first interlayerinsulating layer IL1. The third conductive layer may include a firstsource electrode S1 and a first drain electrode D1 of the firsttransistor T1.

The first source electrode S1 and the first drain electrode D1 of thefirst transistor T1 may each electrically contact the active layer ACT1through a contact hole penetrating the first interlayer insulating layerIL1 and the first gate insulating layer GI. Furthermore, the firstsource electrode S1 may be in electrical contact with the lower metallayer BML through another contact hole. Although not shown in thedrawing, the third conductive layer may further include data lines or acapacitance electrode of a storage capacitor.

A second interlayer insulating layer IL2 may be disposed on the thirdconductive layer. The second interlayer insulating layer IL2 mayfunction as an insulating layer between the third conductive layer andother layers disposed thereon, and may protect the third conductivelayer.

A fourth conductive layer may be disposed on the second interlayerinsulating layer IL2. The fourth conductive layer may include a firstvoltage line VL1, a second voltage line VL2, and a first conductivepattern CDP. A high potential voltage (or a first source voltage) may beapplied to the first voltage line VL1 and supplied to the firsttransistor T1, and a low potential voltage (or a second source voltage)may be applied to the second voltage line VL2 and supplied to a secondelectrode RME2.

The first conductive pattern CDP may be electrically connected to thefirst transistor T1. The first conductive pattern CDP may also be inelectrical contact with a first electrode RME1, which will be describedbelow, and the first transistor T1 may transfer the first source voltageapplied from the first voltage line VL1 to the first electrode RME1.

The buffer layer BL, the first gate insulating layer GI, the firstinterlayer insulating layer IL1, and the second interlayer insulatinglayer IL2 described above may be formed of inorganic layers stacked inan alternating manner. For example, the buffer layer BL, the first gateinsulating layer GI, the first interlayer insulating layer IL1, and thesecond interlayer insulating layer IL2 may be formed as a double layerformed by stacking, or a multilayer formed by alternately stacking,inorganic layers including at least one of silicon oxide (SiOx), siliconnitride (SiNx), and silicon oxynitride (SiOxNy). However, theembodiments are not limited thereto, and the buffer layer BL, the firstgate insulating layer GI, the first interlayer insulating layer IL1, andthe second interlayer insulating layer IL2 may be formed as a singleinorganic layer containing the insulating material described above.

Each of the second conductive layer, the third conductive layer, and thefourth conductive layer may be formed as a single layer or multiplelayers made of at least one of molybdenum (Mo), aluminum (Al), chromium(Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper(Cu), or an alloy thereof. However, the embodiments are not limitedthereto.

A via layer VIA is disposed on the fourth conductive layer. The vialayer VIA may include an organic insulating material, for example, anorganic material such as polyimide (PI), to perform a surfaceplanarization function.

As the display element layer, banks BNL1, BNL2, and BNL3, the electrodesRME, the light emitting elements ED, and the contact electrodes CNE maybe disposed on the via layer VIA. Furthermore, insulating layers PAS1and PAS2 may be disposed on the via layer VIA.

The second bank BNL2 may be disposed directly on the via layer VIA. Thesecond bank BNL2 may be arranged to extend in the first direction DR1from the center of the emission area EMA. The third banks BNL3 may bedisposed directly on the via layer VIA, and may be disposed to be spacedapart from each other in the emission area EMA of the sub-pixel PXn. Forexample, the third bank BNL3 may include sub-banks BNL_A and BNL_B thatare spaced apart from each other in the second direction DR2 with thesecond bank BNL2 interposed therebetween, in each emission area EMA. Thefirst sub-bank BNL_A may be disposed at the left side of the second bankBNL2, and the second sub-bank BNL_B may be disposed at the right sidethereof. The second bank BNL2 and the third bank BNL3 may have a shapeextending in the first direction DR1, and may have a length smaller thanthe length of the area surrounded by the first bank BNL1 in the firstdirection DR1. The second bank BNL2 and the third bank BNL3 may bearranged in the emission area EMA of each sub-pixel PXn, and may formisland-like patterns that have relatively narrow widths and extend in adirection in the entire surface of the display area DPA. It isillustrated in the drawing that the second bank BNL2 and the sub-banksBNL_A and BNL_B of the third bank BNL3 have the same width, but theembodiments are not limited thereto. The second bank BNL2 may have agreater width than the third bank BNL3.

At least a portion of each of the second bank BNL2 and the third bankBNL3 may protrude from the top surface of the via layer VIA. Theprotruding portions of the second bank BNL2 and the third bank BNL3 mayhave inclined side surfaces, and light emitted from the light emittingelement ED may be reflected from the electrodes RME disposed on thesecond bank BNL2 and the third bank BNL3 to be emitted in an upwarddirection of the via layer VIA. However, the embodiments are not limitedthereto, and the second bank BNL2 and the third bank BNL3 may have asemicircular shape or a semi-elliptical shape, the outer surface ofwhich is curved. The second bank BNL2 and the third bank BNL3 mayinclude an organic insulating material such as polyimide (PI), but theembodiments are not limited thereto.

The electrodes RME are disposed for each sub-pixel PXn in a shapeextending in a direction. For example, the electrodes RME may have ashape extending in the first direction DR1 and may be disposed to bespaced apart from each other in the second direction DR2 in eachsub-pixel PXn. The electrodes RME of the display device 10 may includeelectrodes connected directly to the fourth conductive layer under thevia layer VIA through electrode contact holes CTD and CTS penetratingthe via layer VIA. In other embodiments, the display device 10 mayfurther include electrodes that are not directly connected to the fourthconductive layer.

For example, a sub-pixel PXn may include the plurality of electrodes RMEdisposed to extend in the first direction DR1 across the emission areaEMA and the sub-region SA. The electrodes RME of the sub-pixel PXnadjacent in the first direction DR1 may be separated from each other ata separating portion ROP of the sub-region SA. In the fabricatingprocess of the display device 10, the electrodes RME may be formed aselectrode lines extending in the first direction DR1, and may be used togenerate an electric field in the sub-pixel PXn to align the lightemitting elements ED. The light emitting elements ED may be aligned by adielectrophoretic force that is induced by the electric field generatedon the electrode lines, and the electrode lines may be separated at theseparating portion ROP to form the electrodes RME.

The electrodes RME disposed in each sub-pixel PXn may include the firstelectrode RME1, the second electrode RME2, and a third electrode RME3.The first electrode RME1 may be disposed on the second bank BNL2, andthe second electrode RME2 and the third electrode RME3 may berespectively disposed on the sub-banks BNL_A and BNL_B of the third bankBNL3.

The first electrode RME1 may be disposed on the second bank BNL2 in thecenter portion of the emission area EMA. The second electrode RME2 maybe spaced apart from the first electrode RME1 in the second directionDR2, and may be disposed on the first sub-bank BNL_A at the left side ofthe emission area EMA. The third electrode RME3 may be spaced apart fromthe second electrode RME2 in the second direction DR2 with the firstelectrode RME1 interposed therebetween, and may be disposed on thesecond sub-bank BNL_B at the right side of the emission area EMA. Bothsides of the first electrode RME1 may respectively face the secondelectrode RME2 and the third electrode RME3, while being spaced aparttherefrom.

Each of the first electrode RME1 and the second electrode RME2 may be afirst type electrode that is connected to the fourth conductive layerdisposed thereunder. The first electrode RME1 and second electrode RME2may be directly connected to the fourth conductive layer through thefirst electrode contact hole CTD formed in a portion overlapping thefirst bank BNL1 and the second electrode contact hole CTS formed in thesub-region SA, respectively. For example, the first electrode RME1 maybe in contact with the first conductive pattern CDP through the firstelectrode contact hole CTD penetrating the via layer VIA thereunder. Thesecond electrode RME2 may be in contact with the second voltage line VL2through the second electrode contact hole CTS penetrating the via layerVIA thereunder. The first electrode RME1 may be electrically connectedto the first transistor T1 through the first conductive pattern CDP, sothat the first source voltage may be applied to the first electrodeRME1, and the second electrode RME2 may be electrically connected to thesecond voltage line VL2, so that the second source voltage may beapplied to the second electrode RME2. Since the first electrode RME1 andthe second electrode RME2 are disposed for each sub-pixel PXnseparately, the light emitting elements ED of different sub-pixels PXnmay emit light individually.

The third electrode RME3 may be a second type electrode that is notdirectly connected to the fourth conductive layer disposed thereunder,unlike the first type electrode. The electrical signal directly appliedto the first type electrode may be transmitted to the second typeelectrode through the light emitting element ED or the contact electrodeCNE. Although the third electrode RME3 may not be directly connected tothe fourth conductive layer disposed thereunder, it may not be floatedbecause the electrical signal applied from the fourth conductive layeris transmitted thereto.

In an embodiment, among the electrodes RME, the width of the firstelectrode RME1 measured in the second direction DR2 may be greater thanthe second bank BNL2, and the widths of the second electrode RME2 andthe third electrode RM3 measured in the second direction DR2 may besmaller than the third bank BNL3. The first electrode RME1 may bearranged to cover (or overlap) both side surfaces of the second bankBNL2, and each of the second and third electrodes RME2 and RME3 may bearranged to cover (or overlap) a side surface of the third bank BNL3.The electrodes RME may be disposed to cover (or overlap) at least oneside surface of the second bank BNL2 or the third bank BNL3 to reflectlight emitted from the light emitting element ED. The gap between theelectrodes RME in the second direction DR2 may be smaller than the gapbetween the second bank BNL2 and the third bank BNL3. Each of theelectrodes RME may have at least a portion directly disposed on the vialayer VIA, so that they may be disposed on the same plane.

The electrodes RME may be electrically connected to the light emittingelements ED. The electrodes RME may be connected to both ends of thelight emitting element ED through the contact electrodes CNE, and maytransmit an electrical signal applied from the fourth conductive layerto the light emitting element ED. Electrical signals for emitting thelight emitting elements ED may be directly applied to the firstelectrode RME1 and the second electrode RME2, and the electrical signalsmay be transmitted to the other electrodes through the contactelectrodes CNE and light emitting elements ED, which will be describedbelow.

Each of the electrodes RME may include a conductive material having highreflectivity. For example, the electrode RME may include a metal such assilver (Ag), copper (Cu), or aluminum (Al) as a material having highreflectivity, or may be an alloy including aluminum (Al), nickel (Ni),lanthanum (La), and the like. The electrode RME may reflect, in theupward direction of each sub-pixel PXn, light emitted from the lightemitting element ED and traveling to the side surface of the first bankBNL1 or the second bank BNL2.

However, the embodiments are not limited thereto, and each electrode RMEmay further include a transparent conductive material. For example, eachelectrode RME may include a material such as ITO, IZO, and ITZO. In someembodiments, each of the electrodes RME may have a structure in which atleast one transparent conductive material and at least one metal layerhaving high reflectivity are stacked, or may be formed as a single layerincluding them. For example, each electrode RME may have a stackedstructure of ITO/Ag/ITO, ITO/Ag/IZO, ITO/Ag/ITZO/IZO, or the like.

The first insulating layer PAS1 is disposed on the electrodes RME, thesecond bank BNL2 and the third bank BNL3. The first insulating layerPAS1 may be disposed to entirely cover them. The first insulating layerPAS may protect the electrodes RME, while insulating them from eachother. The first insulating layer PAS1 may prevent the light emittingelement ED disposed thereon from being damaged by direct contact withother members.

In an embodiment, the first insulating layer PAS1 may have steppedportions such that the top surface thereof is partially depressedbetween the electrodes RME spaced apart in the second direction DR2. Thelight emitting element ED may be disposed on the top surface of thefirst insulating layer PAS1, where the stepped portions are formed, andthus a space may remain between the light emitting element ED and thefirst insulating layer PAS1. However, the embodiments are not limitedthereto.

The first insulating layer PAS1 may include a contact portions CT1, CT2,and CT3 that expose a portion of the top surface of each electrode RME.The contact portions CT1, CT2, and CT3 may penetrate the firstinsulating layer PAS1, and the contact electrodes CNE, which will bedescribed below, may be in contact with the exposed electrodes RMEthrough the contact portions CT1, CT2, and CT3.

The first bank BNL1 may be disposed on the first insulating layer PAS1.The first bank BNL1 may include portions extending in the firstdirection DR1 and the second direction DR2 in a plan view, and thus maybe arranged in a grid pattern. The first bank BNL1 may be disposed alongthe boundaries between the sub-pixels PXn to delimit the neighboringsub-pixels PXn. Furthermore, the first bank BNL1 may be disposed tosurround the emission area EMA and the sub-region SA disposed for eachsub-pixel PXn to delimit them from each other.

In an embodiment, in the portion of the first bank BNL1 extending in thefirst direction DR1, the portion disposed between the emission areas EMAmay have a greater width than the portion disposed between thesub-regions SA, and the gap between the sub-regions SA may be smallerthan the gap between the emission areas EMA. However, the embodimentsare not limited thereto, and vice versa. The width of the first bankBNL1 may be varied so that the gap between the sub-regions SA may begreater than the gap between the emission areas EMA.

The first bank BNL1 may have a height greater than those of the secondbank BNL2 and the third bank BNL3. The first bank BNL1 may prevent inkfrom overflowing to the adjacent sub-pixel PXn in an inkjet printingstep during the fabricating process of the display device 10. The firstbank BNL1 may separate inks in which different light emitting elementsED are dispersed for different sub-pixels PXn so as not to be mixed witheach other. However, the embodiments are not limited thereto. The firstbank BNL1, the second bank BNL2, and the third bank BNL3 may include thesame material , and may be formed to have substantially similar heights.

The light emitting element ED may be disposed on the first insulatinglayer PAS1. The light emitting elements ED may be disposed to be spacedapart from each other along the first direction DR1 in which theelectrodes RME extend, and may be aligned substantially parallel to eachother. The light emitting element ED may have a shape extending in onedirection, and the extension direction of the light emitting element EDmay be substantially perpendicular to the extension direction of theelectrodes RME. However, the embodiments are not limited thereto, andthe light emitting elements ED may each be arranged to extend in adirection oblique to the extension direction of the electrodes RME.

The light emitting element ED may include semiconductor layers dopedwith different conductivity type dopants. The light emitting element EDmay include semiconductor layers and may be oriented such that one endthereof faces a certain direction according to the direction of theelectric field generated on the electrode RME. The light emittingelement ED may include a light emitting layer 36 (refer to FIG. 9) toemit light of a predetermined wavelength band. The light emittingelement ED aligned in each sub-pixel PXn may emit light of a differentwavelength band according to the material constituting the lightemitting layer 36. However, the embodiments are not limited thereto, andthe light emitting element ED aligned in each sub-pixel PXn may emit thesame color light.

The light emitting element ED may include layers arranged in a directionparallel to the top surface of the first substrate SUB. The lightemitting element ED of the display device 10 may be disposed such thatan extension direction thereof is parallel to the first substrate SUB,and the semiconductor layers included in the light emitting element EDmay be sequentially arranged in a direction parallel to the top surfaceof the first substrate SUB. However, the embodiments are not limitedthereto. In some cases, when the light emitting element ED has adifferent structure, the layers may be arranged in a directionperpendicular to the first substrate SUB.

The light emitting element ED may be disposed above the electrodes RMEthat are spaced apart from each other in the second direction DR2between the second bank BNL2 and the third bank BNL3. The extensionlength of the light emitting element ED may be greater than the gapbetween the electrodes RME spaced apart in the second direction DR2, andboth ends of the light emitting element ED may be disposed on differentelectrodes. For example, the light emitting element ED may include afirst light emitting element ED1 whose both ends are respectivelydisposed on the first electrode RME1 and the third electrode RME3, and asecond light emitting element ED2 whose both ends are respectivelydisposed on the first electrode RME1 and the second electrode RME2.

The light emitting element ED may include semiconductor layers, and afirst end and a second end opposite thereto may be defined with respectto any of the semiconductor layers. The light emitting element ED may bedisposed such that the first end and the second end are respectivelyplaced on specific electrodes RME. For example, the first light emittingelement ED1 may be disposed such that the first end is disposed on thefirst electrode RME1 and the second end is disposed on the thirdelectrode RME3. The second light emitting element ED2 may be disposedsuch that the first end is disposed on the first electrode RME1 and thesecond end is disposed on the second electrode RME2. However, theembodiments are not limited thereto, and the light emitting elements EDmay be disposed such that only one end is placed on the electrode RMEaccording to an orientation thereof between the electrodes RME.

The ends of the light emitting element ED may contact the respectivecontact electrodes CNE. In the light emitting element ED, since aninsulating layer 38 (refer to FIG. 9) is not formed on the end surfacesin the extension direction, and thus the semiconductor layer ispartially exposed, the exposed semiconductor layer may be in contactwith the contact electrode CNE. However, the embodiments are not limitedthereto. In other embodiments, at least a portion of the insulatinglayer 38 of light emitting element ED may be removed, so that the sidesurfaces at the ends of the semiconductor layers may be partiallyexposed. The side surfaces of the exposed semiconductor layer may be indirect contact with the contact electrodes CNE. Each of the lightemitting elements ED may be electrically connected to the electrode RMEor another light emitting element ED through the contact electrode CNE.

The second insulating layer PAS2 may be partially disposed on the firstinsulating layer PAS1 and the light emitting element ED. For example,the second insulating layer PAS2 may be disposed to partially cover theouter surface of the light emitting element ED so as not to cover thefirst and second ends of the light emitting element ED. The portion ofthe second insulating layer PAS2 disposed on the light emitting elementED may be arranged to extend in the first direction DR1 on the firstinsulating layer PAS1 in a plan view, so that it may form a linear orisland-like pattern in each sub-pixel PXn. The second insulating layerPAS2 may protect the light emitting element ED while fixing the lightemitting element ED during the fabricating process of the display device10. The second insulating layer PAS2 may be disposed to fill the spacebetween the light emitting element ED and the first insulating layerPAS1 thereunder.

Furthermore, the second insulating layer PAS2 may also be disposed onthe first bank BNL1. The second insulating layer PAS2 may be disposed onthe first insulating layer PAS1 and the first bank BNL1 while exposingthe ends of the light emitting element ED and partially exposing theportions where the electrodes RME are disposed. The shape of the secondinsulating layer PAS2 may be formed through steps of entirely disposingit on the first insulating layer PAS1 and partially removing it toexpose the ends of the light emitting element ED, during the fabricatingprocess of the display device 10.

The second insulating layer PAS2 may also be partially disposed in thesub-region SA. The electrodes RME may be formed by separating theelectrode lines at the separating portion ROP of the sub-region SA afteraligning the light emitting elements ED and forming the secondinsulating layer PAS2. In the separating step of the electrode line, inaddition to the electrodes RME, the first insulating layer PAS1 and thesecond insulating layer PAS2 may also be partially removed, and the vialayer VIA may be partially exposed in the separating portion ROP.

The contact electrodes CNE may be disposed on the second insulatinglayer PAS2. The contact electrode CNE may be in electrical contact withany one end of the light emitting element ED and at least one electrodeRME. For example, the contact electrode CNE may be in contact with oneend of the light emitting element ED exposed without the secondinsulating layer PAS2 disposed thereon, and at least one of theelectrodes RME through the contact portions CT1, CT2, and CT3 formed inthe first insulating layer PAS1 to partially expose the electrodes RME.Each of the contact electrodes CNE may include a portion extending inthe first direction DR1 to be disposed across the emission area EMA andthe sub-region SA. The contact electrode CNE may include a portiondisposed in the emission area EMA, which is in contact with the lightemitting element ED, and a portion disposed in the sub-region SA, whichis in contact with the electrode RME through the contact portion CT1,CT2, CT3. The contact electrodes CNE may be arranged on the first bankBNL1 disposed between the emission area EMA and the sub-region SA.

According to an embodiment, the contact electrodes CNE of the displaydevice 10 may be classified into different types of contact electrodesthat are electrically connected to different types of electrodes. Forexample, the contact electrode CNE may include a first contact electrodeCNE1 and a second contact electrode CNE2 as first type contactelectrodes disposed on the first electrode RME1 or the second electrodeRME2 that is the first type electrode.

The first contact electrode CNE1 and the second contact electrode CNE2may be disposed on the first electrode RME1 and the second electrodeRME2, respectively. The first contact electrode CNE1 and the secondcontact electrode CNE2 each have a shape extending in the firstdirection DR1, and may form linear patterns in the emission area EMA ofeach sub-pixel PXn. The first contact electrode CNE1 may be in contactwith the first electrode RME1 through the first contact portion CT1 thatexposes the top surface of the first electrode RME1, and the secondcontact electrode CNE2 may be in contact with the second electrode RME2through the second contact portion CT2 that exposes the top surface ofthe second electrode RME2. The first contact electrode CNE1 may be incontact with the first end of the first light emitting element ED1 andthe second contact electrode CNE2 may be in contact with the second endof the second light emitting element ED2.

Each of the first contact electrode CNE1 and the second contactelectrode CNE2 as the first type contact electrode may transmit anelectrical signal applied to the first type electrode to one end of thelight emitting element ED. The electrical signals may be directlyapplied to the first end of the first light emitting element ED1 and thesecond end of the second light emitting element ED2, and transmitted toother contact electrodes CNE and other light emitting elements EDthrough the second end of the first light emitting element ED1 and thefirst end of the second light emitting element ED2.

The contact electrode CNE may include a third contact electrode CNE3 asa second type contact electrode disposed over the third electrode RME3that is the second type electrode and the first electrode RME1 that isthe first type electrode.

The third contact electrode CNE3 may be disposed above the firstelectrode RME1 and the third electrode RME3. The third contact electrodeCNE3 may include a first extension portion CN_E1 and a second extensionportion CN_E2 extending in the first direction DR1, and a firstconnection portion CN_B1 (or connection portion) connecting the firstextension portion CN_E1 to the second extension portion CN_E2. The thirdcontact electrode CNE3 may have a shape substantially surrounding thefirst contact electrode CNE1.

The first extension portion CN_E1 is disposed above the third electrodeRME3, and the second extension portion CN_E2 is disposed above the firstelectrode RME1 while being spaced apart from the first contact electrodeCNE1. The first extension portion CN_E1 may face the first contactelectrode CNE1 while being spaced apart therefrom, and the secondextension portion CN_E2 may face the second contact electrode CNE2 whilebeing spaced apart therefrom. The first extension portion CN_E1 may bein contact with the third electrode RME3 exposed through the thirdcontact portion CT3, but the second extension portion CN_E2 may not bein contact with the first electrode RME1. The first extension portionCN_E1 may be in contact with the second end of the first light emittingelement ED1 and the second extension portion CN_E2 may be in contactwith the first end of the second light emitting element ED2. Anelectrical signal may be transmitted to the third electrode RME3 throughthe third contact electrode CNE3. The first connection portion CN_B1 (orconnection portion) may be disposed on the first bank BNL1 disposedbetween the emission area EMA and the sub-region SA of another sub-pixelPXn in the first direction DR1.

The first light emitting element ED1 may be electrically connected tothe second light emitting element ED2 through the third contactelectrode CNE3. The electrical signal applied to the first contactelectrode CNE1 may be transmitted to the second light emitting elementED2 through the first light emitting element ED1 and the third contactelectrode CNE3. The light emitting elements ED disposed in a sub-pixelPXn may be connected in series via the second type contact electrode.

The contact portions CT1, CT2, and CT3 may be disposed so as not tooverlap the light emitting elements ED in the second direction DR2. Thecontact portions CT1, CT2, and CT3 may be formed to be spaced apart fromthe area, in which the light emitting elements ED are disposed, in thefirst direction DR1. Light may be emitted from the ends of the lightemitting element ED, and the contact portions CT1, CT2, and CT3 may bepositioned away from the traveling paths of the light. In an embodiment,the contact portions CT1, CT2, and CT3 may be formed in the sub-regionSA where the light emitting elements ED are not disposed. As the contactportions CT1, CT2, and CT3 are disposed in the sub-region SA, it may bepossible to minimize light that is not emitted due to the refraction oflight by the contact portions CT1, CT2, CT3. During the fabricatingprocess of the display device 10, by disposing the contact portions CT1,CT2, and CT3 away from where the light emitting elements ED are disposedmay prevent light emitting elements ED from agglomerating near thecontact portions CT1, CT2, and CT3 that expose the top surfaces of theelectrodes RME, which may attract the light emitting elements ED.

The contact electrodes CNE may be disposed on the second insulatinglayer PAS2 to be spaced apart from each other, but may be disposeddirectly on the first insulating layer PAS1 and the light emittingelement ED in portions where the second insulating layer PAS2 is notdisposed. However, the embodiments are not limited thereto, and otherinsulating layers may be further disposed between the contact electrodesCNE, so that some of the contact electrodes CNE may be disposed on thesame layer and others may be disposed on a different layer.

The contact electrode CNE may include a conductive material. Forexample, it may include ITO, IZO, ITZO, aluminum (Al), or the like. Asan example, the contact electrodes CNE may include a transparentconductive material, and light emitted from the light emitting elementED may pass through the contact electrodes CNE and proceed toward theelectrodes RME. However, the embodiments are not limited thereto.

Although not shown in the drawing, an insulating layer may be furtherdisposed on the contact electrodes CNE to cover them. The insulatinglayer may be disposed all over the first substrate SUB to protect themembers disposed on the first substrate SUB from the externalenvironment.

Each of the first insulating layer PAS1 and the second insulating layerPAS2 described above may include an inorganic insulating material or anorganic insulating material. However, the embodiments are not limitedthereto.

As described above, in the display device 10 according to an embodiment,the first bank BNL1 may include the trench portions TP having arelatively low height in order to decrease the height difference fromthe emission area EMA and the sub-region SA. Each of the trench portionsTP of the first bank BNL1 may form a space in which the contactelectrode CNE disposed across the emission area EMA and the sub-regionSA may be placed, thereby preventing the material of the contactelectrode CNE from being broken due to the height difference of thefirst bank BNL1.

FIG. 6 is a schematic plan view illustrating a schematic arrangement ofa first bank and a contact electrodes disposed in a sub-pixel of adisplay device according to an embodiment. FIG. 7 is a schematiccross-sectional view taken along line Q5-Q5′ of FIG. 6. FIG. 8 is aschematic cross-sectional view taken along line Q6-Q6′ of FIG. 6. FIG. 6illustrates a relative arrangement of the first bank BNL1 and thecontact electrodes CNE of a sub-pixel PXn. FIG. 7 illustrates across-section through the trench portions TP of the first bank BNL1, andFIG. 8 illustrates a cross-section through openings OP of the secondinsulating layer PAS2 adjacent to the trench portion TP.

Referring to FIGS. 6 and 7 in conjunction with FIG. 3, in the displaydevice 10 according to an embodiment, the first bank BNL1 may includethe trench portions TP having a lower height than other portions. Thefirst bank BNL1 has a predetermined height, and is disposed to surroundthe emission area EMA and the sub-region SA. The first bank BNL1 mayinclude the trench portions TP, in which the top surface of the firstbank BNL1 is partially depressed, in a region between the emission areaEMA and the sub-region SA.

For example, the first bank BNL1 includes a first trench portion TP1 anda second trench portion TP2 disposed on an upper side (in the firstdirection DR1) of the emission area EMA, between the emission area EMAand the sub-region SA of the corresponding sub-pixel PXn. The first bankBNL1 may further include a third trench portion TP3 disposed on a lowerside (in the first direction DR1) of the emission area EMA between theemission area EMA and the sub-region SA of another sub-pixel PXn. Thefirst bank BNL1 may be divided into a first bank portion BP1 that has apredetermined height, and a second bank portion BP2 that includes thetrench portions TP formed therein and thus has a height lower than thefirst bank portion BP1.

The first trench portion TP1 and the second trench portion TP2 may bespaced apart from each other in the second direction DR2 between theemission area EMA and the sub-region SA of the sub-pixel PXn. A firstbridge bank portion BR1 (or bridge bank portion) having the same heightas the first bank portion BP1 may be disposed between the first trenchportion TP1 and the second trench portion TP2. The first bridge bankportion BR1 (or bridge bank portion) may extend in the first directionDR1 between the first trench portion TP1 and the second trench portionTP2 and may be in contact with the emission area EMA and the sub-regionSA.

As going from the emission area EMA to the sub-region SA, a heightdifference may occur by the first bank BNL1 disposed therebetween. Inthe first bank BNL1, since the second bank portion BP2 where the trenchportion TP is formed has a relatively low height compared to the firstbank portion BP1, it is possible to decrease the height differencebetween the first bank BNL1, and the emission area EMA and thesub-region SA. Similarly, the third trench portion TP3 is disposedbetween the emission area EMA and the sub-region SA of differentsub-pixels PXn, thereby decreasing the height difference by the firstbank BNL1.

In some embodiments, the third trench portion TP3 may have a widthgreater than the first trench portion TP1 and the second trench portionTP2. However, the embodiments are not limited thereto, and the widths ofthe trench portions TP may vary. In some embodiments, the first trenchportion TP1 may be connected to the second trench portion TP2, togetherforming a trench portion TP. The first bridge bank portion BR1 (orbridge bank portion) between the first trench portion TP1 and the secondtrench portion TP2 may be omitted.

According to an embodiment, the second insulating layer PAS2 may bedisposed on the first bank BNL1, and the second insulating layer PAS2may include the openings OP corresponding to the trench portions TP ofthe first bank BNL1. The second insulating layer PAS2 may not bedisposed in the trench portions TP. The top surface of the first bankBNL1 or the first insulating layer PAS1 may be partially exposed throughthe openings OP. The openings OP of the second insulating layer PAS2 maybe located to correspond to the trench portions TP of the first bankBNL1, but may occupy greater areas than the trench portions TP in a planview. The top surface of the first bank BNL1 or the first insulatinglayer PAS1, which may be located in the opening OP of the secondinsulating layer PAS2, may be .

As shown in FIG. 7, the second insulating layer PAS2 may not be disposedon the first trench portion TP1 and the second trench portion TP2 sothat the top surface of the first bank BNL1 in the trench portions TP1and TP2 may be exposed, and the second insulating layer PAS2 may bedisposed on the first bank portion BP1 and the first bridge bank portionBR1 (or bridge bank portion) that are regions other than the trenchportion TP. In an embodiment, the second insulating layer PAS2 mayinclude a first bridge pattern IP1 disposed on the first bridge bankportion BR1 (or bridge bank portion). The first bridge pattern IP1 mayhave a shape extending in the first direction DR1 between the emissionarea EMA and the sub-region SA. The first bridge pattern IP1 may connecta portion of the second insulating layer PAS2 disposed in the emissionarea EMA to a portion of the second insulating layer PAS2 disposed inthe sub-region SA.

As illustrated in FIG. 8, among the openings OP of the second insulatinglayer PAS2, the opening disposed in the emission area EMA may expose thetop surface of the first insulating layer PAS1 directly. The secondinsulating layer PAS2 may include not only the portions exposing bothends of the light emitting element ED but also the openings OP formed tocorrespond to the trench portions TP of the first bank BNL1 to partiallyexpose the top surface of the first insulating layer PAS1 or the firstbank BNL1.

According to an embodiment, the sidewall of the trench portion TP of thefirst bank BNL1 may be aligned with the sidewall of the secondinsulating layer PAS2 disposed on the first bank portion BP1. As will bedescribed below, a step of forming the trench portion TP of the firstbank BNL1 may be performed simultaneously with a step of forming theopening OP of the second insulating layer PAS2. Since the trench portionTP and the opening OP may be formed in the same step, the sidewall ofthe trench portion TP of the first bank BNL1 may be aligned with thesidewall of the second insulating layer PAS2.

The contact electrodes CNE may be disposed across the emission area EMAand the sub-region SA, and may also be disposed on the first bank BNL1between the emission area EMA and the sub-region SA. The trench portionsTP of the first bank BNL1 may provide spaces in which the contactelectrodes CNE are arranged across the emission area EMA and thesub-region SA. The first trench portion TP1 may overlap the firstcontact electrode CNE1 and the first extension portion CN_E1 of thethird contact electrode CNE3, and the second trench portion TP2 mayoverlap the second contact electrode CNE2. The third trench portion TP3may overlap the first connection portion CN_B1 (or connection portion)of the third contact electrode CNE3. The contact electrodes CNE disposedon the second insulating layer PAS2 in the emission area EMA may bedirectly arranged on the first bank BNL1 in the trench portion TP of thefirst bank BNL1. Furthermore, the contact electrodes CNE may be directlyarranged on the first insulating layer PAS1 in the opening OP of thesecond insulating layer PAS2 formed in the region adjacent to the trenchportion TP.

In the fabricating process of the display device 10, the light emittingelements ED may be aligned by an electric field generated on theelectrode line. The electrode line is separated in a subsequentprocessing step to form the electrodes RME, and the first insulatinglayer PAS1 including the contact portions CT1, CT2, and CT3 formedtherein may be disposed on the electrode lines. The electric fieldgenerated on the electrode line may have a relatively strong intensityin regions adjacent to the contact portions CT1, CT2 and CT3 throughwhich the top surface of the electrode line is exposed. In order toprevent the light emitting elements ED from gathering near the contactportions CT1, CT2, and CT3, the display device 10 may include the firstbank BNL1 surrounding the emission area EMA and the sub-region SA, andthe contact portions CT1, CT2, and CT3 may be disposed in the sub-regionSA, and not disposed in the emission area EMA. The top surfaces of theelectrodes RME may be partially exposed in the sub-region SA, but notexposed in the emission area EMA.

Since the light emitting elements ED are disposed on the electrodes RMEin the emission area EMA, the contact electrodes CNE in contact with thelight emitting elements ED and the electrodes RME may be disposed acrossthe emission area EMA and the sub-region SA. The first bank BNL1 havinga predetermined height may be disposed between the emission area EMA andthe sub-region SA, and the emission area EMA and the sub-region SA mayhave heights lower than the first bank BNL1. From the emission area EMAto the sub-region SA in the first direction DR1, a height difference mayoccur by the first bank BNL1.

In order to partially decrease the height difference by the first bankBNL1, the display device 10 according to an embodiment may include thetrench portion TP at which the first bank BNL1 has a lower height thanother parts of the first bank BNL1. The trench portion TP may extend inthe first direction DR1 to form a space in which the contact electrodesCNE disposed across the emission area EMA and the sub-region SA areplaced. The contact electrodes CNE are disposed from the emission areaEMA, in which the first bank BNL1 is not disposed, to the sub-region SAthrough the trench portion TP of the first bank BNL1. As the contactelectrodes CNE are arranged on the relatively low trench portion TP, itis possible to prevent material breakage due to a lower stepped portion.By decreasing the slope of the first bank BNL1, different contactelectrodes CNE can be prevented from being short-circuited due toresidues of a material used in a step of forming the contact electrodesCNE.

FIG. 9 is a schematic diagram of a light emitting element according toan embodiment.

Referring to FIG. 9, the light emitting element ED may be a lightemitting diode. Specifically, the light emitting element ED may be aninorganic light emitting diode that has a nanometer or micrometer size,and is made of an inorganic material. The light emitting element ED maybe aligned between two electrodes having polarity when an electric fieldis formed in a specific direction between two electrodes opposing eachother.

The light emitting element ED according to an embodiment may have anelongated shape. The light emitting element ED may have a shape of acylinder, a rod, a wire, a tube, or the like. However, the shape of thelight emitting element ED is not limited thereto, and the light emittingelement ED may have a polygonal prism shape such as a regular cube, arectangular parallelepiped, and a hexagonal prism, or may have variousshapes such as a shape elongated in one direction and having an outersurface partially inclined.

The light emitting element ED may include a semiconductor layer dopedwith any conductivity type (e.g., p-type or n-type) impurities. Thesemiconductor layer may emit light of a specific wavelength band byreceiving an electrical signal applied from an external power source.The light emitting element ED may include a first semiconductor layer31, a second semiconductor layer 32, a light emitting layer 36, anelectrode layer 37 and an insulating layer 38.

The first semiconductor layer 31 may be an n-type semiconductor. Thefirst semiconductor layer 31 may include a semiconductor material havinga chemical formula of AlxGayIn1-x-yN (0≤x≤1, 0≤y≤1, 0≤x+y≤1). Forexample, it may include at least one or more of n-type doped AlGaInN,GaN, AlGaN, InGaN, MN and InN. The n-type dopant doped into the firstsemiconductor layer 31 may be Si, Ge, Sn, or the like. The first end ofthe light emitting element ED may be a portion in which the firstsemiconductor layer 31 is disposed in relation to the light emittinglayer 36.

The second semiconductor layer 32 is disposed on the first semiconductorlayer 31 with the light emitting layer 36 therebetween. The secondsemiconductor layer 32 may be a p-type semiconductor, and the secondsemiconductor layer 32 may include a semiconductor material having achemical formula of AlxGayIn1-x-yN (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example,it may include at least one or more of p-type doped AlGaInN, GaN, AlGaN,InGaN, MN and InN. The p-type dopant doped into the second semiconductorlayer 32 may be Mg, Zn, Ca, Se, Ba, or the like. The second end of thelight emitting element ED may be a portion in which the secondsemiconductor layer 32 is disposed in relation to the light emittinglayer 36.

Although it is illustrated in the drawing that the first semiconductorlayer 31 and the second semiconductor layer 32 are configured as onelayer, the embodiments are not limited thereto. Depending on thematerial of the light emitting layer 36, the first semiconductor layer31 and the second semiconductor layer 32 may further include a largernumber of layers, such as a cladding layer or a tensile strain barrierreducing (TSBR) layer.

The light emitting layer 36 is disposed between the first semiconductorlayer 31 and the second semiconductor layer 32. The light emitting layer36 may include a material having a single or multiple quantum wellstructure. When the light emitting layer 36 includes a material having amultiple quantum well structure, quantum layers and well layers may bestacked alternately. The light emitting layer 36 may emit light bycoupling of electron-hole pairs according to an electrical signalapplied through the first semiconductor layer 31 and the secondsemiconductor layer 32. The light emitting layer 36 may include amaterial such as AlGaN or AlGaInN. In case that the light emitting layer36 has a structure in which quantum layers and well layers arealternately stacked in a multiple quantum well structure, the quantumlayer may include a material such as AlGaN or AlGaInN, and the welllayer may include a material such as GaN or AlInN.

The light emitting layer 36 may have a structure in which semiconductormaterials having large band gap energy and semiconductor materialshaving small band gap energy are alternately stacked, and may includeother group III to V semiconductor materials according to the wavelengthband of the emitted light. The light emitted by the light emitting layer36 is not limited to light of a blue wavelength band, but the activelayer 36 may also emit light of a red or green wavelength band in somecases.

The electrode layer 37 may be an ohmic contact electrode. However, theembodiments are not limited thereto, and it may be a Schottky contactelectrode. The light emitting element ED may include at least oneelectrode layer 37. The light emitting element ED may include one ormore electrode layers 37, but the embodiments are not limited thereto,and the electrode layer 37 may be omitted.

In the display device 10, when the light emitting element ED iselectrically connected to an electrode or a contact electrode, theelectrode layer 37 may reduce the resistance between the light emittingelement ED and the electrode or contact electrode. The electrode layer37 may include conductive metal. For example, the electrode layer 370may include at least one of aluminum (Al), titanium (Ti), indium (In),gold (Au), silver (Ag), ITO, IZO, and ITZO.

The insulating layer 38 may be arranged to surround the outer surfacesof the semiconductor layers and electrode layers described above. Forexample, the insulating layer 38 may be disposed to surround at leastthe outer surface of the light emitting layer 36, and may be formed toexpose both ends of the light emitting element ED in the longitudinaldirection. In a cross-sectional view, the insulating layer 38 may have atop surface, which is rounded in a region adjacent to at least one endof the light emitting element ED.

The insulating layer 38 may include a material having insulatingproperties, such as silicon oxide (SiOx), silicon nitride (SiNx),silicon oxynitride (SiOxNy), aluminum nitride (AlNx), and aluminum oxideAlOx). It is illustrated in the drawing that the insulating layer 38 isformed as a single layer, but the embodiments are not limited thereto.In some embodiments, the insulating layer 38 may be formed in amultilayer structure having layers stacked therein.

The insulating layer 38 may function to protect the members. Theinsulating layer 38 may prevent an electrical short circuit that islikely to occur at the light emitting layer 36 when an electrode towhich an electrical signal is transmitted is in direct contact with thelight emitting element ED. The insulating layer 38 may prevent adecrease in light emission efficiency of the light emitting element ED.

The insulating layer 38 may have an outer surface which issurface-treated. The light emitting elements ED may be aligned in such away of spraying the ink in which the light emitting elements ED aredispersed on the electrodes. Here, the surface of the insulating layer38 may be treated in a hydrophobic or hydrophilic manner in order tokeep the light emitting elements ED in a dispersed state withoutagglomerating with other light emitting elements ED adjacent in the ink.

Hereinafter, a fabricating process of the display device 10 will bedescribed with further reference to other drawings.

FIGS. 10 to 15 are schematic views illustrating a portion of afabricating process of a display device according to an embodiment.FIGS. 10 to 15 illustrate a step of forming the second insulating layerPAS2 disposed on the light emitting element ED in the emission area EMA,and a step of forming the first bank BNL 1 in the region between theemission area EMA and the sub-region SA, sequentially. FIGS. 10, 12, and14 illustrate the step of forming the second insulating layer PAS2 inthe emission area EMA, which corresponds to the portion on line Q2-Q2′of FIG. 4, and FIGS. 11, 13, and 15 illustrates the step of forming thefirst bank BNL1 in the region between the emission area EMA and thesub-region SA, which corresponds to FIG. 7.

First, referring to FIGS. 10 and 11, the first substrate SUB isprepared, the circuit layer CCL, the second bank BNL2, the third bankBNL3, the electrodes RME, the first insulating layer PAS1, and a firstbank layer BN1 are formed on the first substrate SUB, and the lightemitting elements ED are disposed on the electrodes RME.

The first bank layer BN1 may be formed to surround the emission area EMAand the sub-region SA. The first bank layer BN1 may be formed to havethe same height as the first bank portion BP1 of FIG. 7. The first banklayer BN1 may prevent overflow of ink including the light emittingelement ED in a subsequent step.

In the display device 10 according to an embodiment, the light emittingelements ED may be disposed on the electrodes RME through an inkjetprinting step. The light emitting element ED including semiconductorlayers doped with different conductivity types may have intramolecularinteraction, (e.g., dipole-dipole interaction), and may be disposed onthe electrode lines by a dielectrophoretic force induced by an electricfield in ink.

Ink sprayed to each sub-pixel PXn may be seated in the emission area EMAsurrounded by the first bank layer BN1. The first bank layer BN1 mayprevent the ink from overflowing into the adjacent emission area EMA.Furthermore, even if inks including different types of light emittingelements ED are sprayed to different sub-pixels PXn, they may beprevented from being mixed.

Subsequently, a first insulating material layer PI1 is formed on thefirst bank layer BN1 to cover the light emitting elements ED. The firstbank layer BN1 and the first insulating material layer PI1 may bepatterned in a subsequent step to form the first bank BNL1 and thesecond insulating layer PAS2 of the display device 10 according to anembodiment. The first insulating material layer PI1 may fix the lightemitting elements ED to the arranged locations while protecting them.

Referring to FIGS. 12 to 15, a photoresist PR is formed on the firstinsulating material layer PI1, and the first insulating material layerPI1 and the first bank layer BN1 are patterned along the photoresist PRto form the second insulating layer PAS2 and the first bank BNL1. Thephotoresist PR may be disposed while partially exposing the top surfaceof the first insulating material layer PI1. The photoresist PR may bedisposed on the first insulating material layer PI1 to correspond to theportions where the second insulating layer PAS2 is formed, shown inFIGS. 4 and 7.

According to an embodiment, in the step of forming the second insulatinglayer PAS2 by patterning the first insulating material layer PI1, thetop surface of the first bank layer BN1 may be partially removedtogether to form the trench portions TP of the first bank BNL1. In someembodiments, since the second insulating layer PAS2 includes aninorganic insulating material, and the first bank BNL1 includes anorganic insulating material, the organic insulating material may also beremoved together in the patterning step of the inorganic insulatingmaterial. When patterning the portion of the first insulating materiallayer PI1, which is exposed without the photoresist PR disposed thereon,the first bank layer BN1 disposed thereunder may also be partiallyremoved. The portion of the first bank layer BN1, from which thematerial has been removed, may have a lower height than other portions.In the patterning step for forming the second insulating layer PAS2, thefirst bank layer BN1 may also be partially patterned to form the firstbank BNL1 including the trench portions TP.

Although not shown in the drawing, the contact electrodes CNE are formedon the second insulating layer PAS2 to fabricate the display device 10.

Hereinafter, other embodiments of the display device 10 will bedescribed with reference to other drawings.

FIG. 16 is a schematic plan view illustrating a sub-pixel of a displaydevice according to an embodiment. FIG. 17 is a schematiccross-sectional view taken along line Q7-Q7′ of FIG. 16. FIG. 17illustrates a cross-section through a holes H of a first bank BNL1_1.

Referring to FIGS. 16 and 17, a display device 10_1 according to anembodiment may include the holes H that are disposed between theemission area EMA and the sub-region SA to partially expose the topsurface of the first insulating layer PAS1. The display device 10_1 mayinclude the holes H formed by removing the first bank BNL1_1 in order tosecure a space in which the contact electrodes CNE are disposed acrossthe emission area EMA and the sub-region SA. The display device 10_1according to the embodiment is different from the embodiment of FIG. 3in that the first bank BNL1_1 does not include the trench portions TP,and the holes H that expose the first insulating layer PAS1 are formedwithout the first bank BNL1_1 disposed therein. In the followingdescription, redundant descriptions will be omitted, and the differenceswill be described.

The holes H of the display device 10_1 may be formed parallel toportions of the first bank BNL1_1 that extend in the second directionDR2 between the emission area EMA and the sub-region SA. For example,the holes H of the display device 10_1 include a first hole H1 and asecond hole H2 disposed on the upper side (in the first direction DR1)of the emission area EMA between the emission area EMA and thesub-region SA of the corresponding sub-pixel PXn. The display device10_1 may further include a third hole H3 disposed on the lower side (inthe first direction DR1) of the emission area EMA between the emissionarea EMA and the sub-region SA of another sub-pixel PXn. Like theemission area EMA and the sub-region SA, the holes H may besubstantially surrounded by the first bank BNL1_1. The emission area EMAmay be connected to the sub-region SA through the holes H.

A first bridge bank portion BR1_1 (or bridge bank portion) of the firstbank BNL1_1 may be disposed between the first hole H1 and the secondhole H2. The first bridge bank portion BR1_1 (or bridge bank portion)may be spaced apart from the first bank portion BP1 of the first bankBNL1_1 in the second direction DR2, and may remain as a pattern whichhas a shape extending in the first direction DR1 between the emissionarea EMA and the sub-region SA.

Unlike the embodiment of FIG. 7, in the display device 10_1 according toan embodiment, the contact electrodes CNE may be disposed across theemission area EMA and the sub-region SA through the holes H. The contactelectrodes CNE arranged in the holes H may be disposed directly on thefirst insulating layer PAS1 exposed by the holes H. As in the embodimentof FIG. 7, the first insulating layer PAS1 includes contact portionsCT1, CT2, and CT3 in the sub-region SA and the contact electrodes CNEelectrically contact the electrodes RME in the contact portions CT1,CT2, and CT3.

The first bank BNL1_1 may have a shape in which the portion thereofextending in the second direction DR2 is separated by the holes Hbetween the emission area EMA and the sub-region SA. The first bankBNL1_1 may include the first bridge bank portion BR1_1 (or bridge bankportion) disposed between the holes H while surrounding the emissionarea EMA and the sub-region SA. This structure of the first bank BNL1_1may be formed by a step of completely removing the remaining portions ofthe first bank layer BN1, after partially patterning the portions of thefirst bank layer BN1 when the openings OP of the second insulating layerPAS2 are formed, in the fabricating process of the display device 10_1.

FIG. 18 is a schematic cross-sectional view illustrating a step in afabricating process of the display device of FIG. 16.

Referring to FIG. 18, during the fabricating process of the displaydevice 10_1 according to an embodiment, a step of removing the exposedfirst bank layer BN1 may be further performed after the step of formingthe second insulating layer PAS2. When the second insulating layer PAS2is patterned, the first bank layer BN1 may be partially removed to formtrench portions. When the trench portions of the first bank layer BN1are completely removed by ashing, the holes H that connect the emissionarea EMA to the sub-region SA may be formed. Since the holes H of thedisplay device 10_1 is also formed by etching the first bank layer BN1together in the patterning step of the second insulating layer PAS2, thesidewall of the first bank BNL1_1 around the hole H may be aligned withthe sidewall of the second insulating layer PAS2 disposed on the firstbank BNL1_1. The second insulating layer PAS2 is not disposed in theholes H. Since the first insulating layer PAS1 and the second insulatinglayer PAS2 contain different materials, the first insulating layer PAS1may not be removed even if the first bank layer BN1 is ashed. Afterashing the first bank layer BN1 to form the holes H, the contactelectrodes CNE are formed on the exposed first insulating layer PAS1 tofabricate the display device 10_1 of FIGS. 16 and 17.

FIG. 19 is a schematic plan view illustrating a sub-pixel of a displaydevice according to an embodiment. FIG. 20 is a schematiccross-sectional view taken along line Q8-Q8′ of FIG. 19. FIG. 21 is aschematic cross-sectional view taken along line Q9-Q9′ of FIG. 19.

Referring to FIGS. 19 to 21, a display device 10_2 according to anembodiment may further include a third insulating layer PAS3. The thirdinsulating layer PAS3 may be disposed on a third contact electrodeCNE3_2 and the second insulating layer PAS2, and a first contactelectrode CNE1_2 and a second contact electrode CNE2 _2 may be arrangedon the third insulating layer PAS3. The third insulating layer PAS3 mayinsulate the first contact electrode CNE1_2 and the second contactelectrode CNE2_2 from the third contact electrode CNE3_2 in order toprevent direct contact therebetween.

In an embodiment, the third insulating layer PAS3 may be disposed on thetrench portion TP of the first bank BNL1 as well as the secondinsulating layer PAS2. In the trench portion TP of the first bank BNL1,the third insulating layer PAS3 may be disposed directly on the firstbank BNL1 exposed by the opening OP of the second insulating layer PAS2,and may cover the side surfaces of the first bridge bank portion BR1 (orbridge bank portion) and the first bridge pattern IP 1.

The third contact electrode CNE3_2 may be disposed directly on thesecond bank portion BP2 of the first bank BNL1 in the first trenchportion TP1, and may be covered by the third insulating layer PAS3disposed thereon. The third contact electrode CNE3_2 may be disposedbetween the first bank BNL1 and the third insulating layer PAS3 in thefirst trench portion TP1. The first contact electrode CNE1_2 and thesecond contact electrode CNE2_2 may be disposed directly on the thirdinsulating layer PAS3 in the first trench portion TP1 and the secondtrench portion TP2, respectively. Thus, the first contact electrodeCNE1_2 and the second contact electrode CNE2_2 may be directly disposedon the third insulating layer PAS3 in the second bank portion BP2. Theembodiment is characterized in that the display device 10_2 furtherincludes the third insulating layer PAS3, and thus the first contactelectrode CNE1_2 and the second contact electrode CNE2_2 are arranged onthe different layer from the third contact electrode CNE3_2.

Embodiments have been disclosed herein, and although terms are employed,they are used and are to be interpreted in a generic and descriptivesense only and not for purpose of limitation. In some instances, aswould be apparent by one of ordinary skill in the art, features,characteristics, and/or elements described in connection with anembodiment may be used singly or in combination with features,characteristics, and/or elements described in connection with otherembodiments unless otherwise specifically indicated. Accordingly, itwill be understood by those of ordinary skill in the art that variouschanges in form and details may be made without departing from thespirit and scope of the disclosure as set forth in the following claims.

What is claimed is:
 1. A display device comprising: an emission area anda sub-region spaced apart from the emission area in a first direction;electrodes extending in the first direction, disposed across theemission area and the sub-region, and spaced apart from each other in asecond direction; a first bank surrounding the emission area and thesub-region; and light emitting elements disposed on the electrodesspaced apart in the second direction in the emission area, wherein thefirst bank includes trench portions in which a top surface of the firstbank is partially depressed, the trench portions being disposed betweenthe emission area and the sub-region.
 2. The display device of claim 1,further comprising contact electrodes disposed on the electrodes andextending in the first direction, wherein the contact electrodes aredisposed across the emission area and the sub-region through the trenchportions of the first bank.
 3. The display device of claim 2, whereinthe first bank includes: a first bank portion; a second bank portionincluding the trench portions, the second bank portion having a heightlower than a height of the first bank portion; and a bridge bank portiondisposed between the trench portions and having a same height as theheight of the first bank portion.
 4. The display device of claim 2,further comprising a first insulating layer covering the electrodes,wherein the first insulating layer includes contact portions partiallyexposing top surfaces of the electrodes in the sub-region.
 5. Thedisplay device of claim 4, wherein the contact electrodes electricallycontact the light emitting elements disposed in the emission area, andelectrically contact the electrodes exposed through the contact portionsin the sub-region.
 6. The display device of claim 4, further comprisinga second insulating layer disposed on the first insulating layer, thefirst bank, and the light emitting elements, wherein the secondinsulating layer exposes ends of the light emitting elements, and thesecond insulating layer is not disposed in the trench portions of thefirst bank.
 7. The display device of claim 6, wherein the contactelectrodes are disposed on the second insulating layer, and are directlydisposed on the second bank portion in the trench portions.
 8. Thedisplay device of claim 6, wherein each of the trench portions of thefirst bank has a sidewall aligned with a sidewall of the secondinsulating layer disposed on the first bank.
 9. The display device ofclaim 6, wherein the second insulating layer includes openings adjacentto the trench portions in the emission area and exposing a top surfaceof the first insulating layer, and the contact electrodes are directlydisposed on the first insulating layer in the openings.
 10. The displaydevice of claim 6, further comprising a third insulating layer disposedon at least one of the contact electrodes and the second insulatinglayer, wherein at least a portion of the contact electrodes is directlydisposed on the third insulating layer in the second bank portion. 11.The display device of claim 10, wherein at least a portion of thecontact electrodes is disposed between the first bank and the thirdinsulating layer in the trench portions.
 12. The display device of claim1, wherein the electrodes include a first electrode and a secondelectrode spaced apart from the first electrode in the second direction,the display device further includes: a first contact electrode disposedon the first electrode and extending in the first direction; and asecond contact electrode disposed on the second electrode and extendingin the first direction, and the trench portions include: a first trenchportion in which the first contact electrode is disposed; and a secondtrench portion in which the second contact electrode is disposed, thesecond trench portion being spaced apart from the first trench portionin the second direction.
 13. The display device of claim 12, wherein theelectrodes further include a third electrode spaced apart from thesecond electrode in the second direction, the first electrode beingdisposed between the second electrode and the third electrode, and thelight emitting elements include: a first light emitting element having afirst end disposed on the first electrode, and a second end disposed onthe third electrode; and a second light emitting element having a firstend disposed on the first electrode, and a second end disposed on thesecond electrode.
 14. The display device of claim 13, further comprisinga third contact electrode including: a first extension portion disposedon the third electrode and electrically contact the second end of thefirst light emitting element; a second extension portion disposed on thefirst electrode and electrically contact the first end of the secondlight emitting element; and a connection portion connecting the firstextension portion to the second extension portion, wherein the firstextension portion extends in the first direction and is disposed acrossthe emission area and the sub-region through the first trench portion.15. The display device of claim 14, wherein the trench portions furtherinclude a third trench portion located opposite the first trench portionin the first direction with respect to the emission area, and theconnection portion is disposed on the third trench portion.
 16. Adisplay device comprising: an emission area and a sub-region spacedapart from the emission area in a first direction; holes disposedbetween the emission area and the sub-region; electrodes extending inthe first direction, disposed across the emission area and thesub-region, and spaced apart from each other in a second direction; afirst bank surrounding the emission area and the sub-region andincluding a bridge bank portion disposed between the holes; lightemitting elements disposed on the electrodes spaced apart in the seconddirection in the emission area; and a contact electrodes disposed on theelectrodes and extending in the first direction, wherein the holesconnect the emission area to the sub-region, and the contact electrodesare disposed across the emission area and the sub-region through theholes.
 17. The display device of claim 16, further comprising: a firstinsulating layer covering the electrodes; and a second insulating layerdisposed on the first insulating layer, the first bank, and the lightemitting elements to expose ends of the light emitting elements, whereinthe second insulating layer is not disposed in the holes.
 18. Thedisplay device of claim 17, wherein the contact electrodes are disposedon the second insulating layer that electrically contacts the lightemitting elements, and are directly disposed on the first insulatinglayer in the holes.
 19. The display device of claim 17, wherein thefirst insulating layer includes contact portions formed in thesub-region to partially expose top surfaces of the electrodes, and thecontact electrodes electrically contact the electrodes in the contactportions of the sub-region.
 20. The display device of claim 17, whereina sidewall of the first bank around the holes is aligned with a sidewallof the second insulating layer disposed on the first bank.